fix: correct native XLM SAC defaults and add derivation-based test

.env.example

@@ -45,8 +45,8 @@ POLL_INTERVAL_MS=6000
 # ─── SAC Contract IDs ────────────────────────────────────────
 # Comma-separated list of Soroban SAC (Stellar Asset Contract) IDs to watch.
 # When unset, defaults to the native XLM SAC for the configured STELLAR_NETWORK:
-#   testnet  → CDMLFMKMMD7MWZP3FKUBZPVHTUEDLSX4BYGYKH4GCESXYHS3IHQ4EIG4
-#   mainnet  → CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC
+#   testnet  → CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC
+#   mainnet  → CAS3J7GYLGXMF6TDJBBYYSE3HQ6BBSMLNUQ34T6TZMYMW2EVH34XOWMA
 #
 # How to derive a SAC address for any Stellar asset:
 #   import { Asset, Networks } from '@stellar/stellar-sdk';
@@ -57,15 +57,15 @@ POLL_INTERVAL_MS=6000
 #     .contractId(Networks.PUBLIC);
 #
 # Known mainnet SAC addresses:
-#   XLM (native): CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC
-#   USDC (Centre): CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA
+#   XLM (native): CAS3J7GYLGXMF6TDJBBYYSE3HQ6BBSMLNUQ34T6TZMYMW2EVH34XOWMA
+#   USDC (Centre): CCW67TSZV3SSS2HXMBQ5JFGCKJNXKZM7UQUWUZPUTHXSTZLEO7SJMI75
 #
 # Example (watch XLM + USDC on mainnet):
-#   SAC_CONTRACT_IDS=CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC,CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA
+#   SAC_CONTRACT_IDS=CAS3J7GYLGXMF6TDJBBYYSE3HQ6BBSMLNUQ34T6TZMYMW2EVH34XOWMA,CCW67TSZV3SSS2HXMBQ5JFGCKJNXKZM7UQUWUZPUTHXSTZLEO7SJMI75
 #
 # Per-network watch lists (for dual-network deployments when NETWORKS=testnet,mainnet):
-#   SAC_CONTRACT_IDS_TESTNET=CDMLFMKMMD7MWZP3FKUBZPVHTUEDLSX4BYGYKH4GCESXYHS3IHQ4EIG4
-#   SAC_CONTRACT_IDS_MAINNET=CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC
+#   SAC_CONTRACT_IDS_TESTNET=CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC
+#   SAC_CONTRACT_IDS_MAINNET=CAS3J7GYLGXMF6TDJBBYYSE3HQ6BBSMLNUQ34T6TZMYMW2EVH34XOWMA
 #
 # Soroban RPC's getEvents accepts multiple contract IDs in a single request —
 # there is no N+1 query penalty for watching multiple contracts.

src/__tests__/multiNetworkIndexer.test.ts

@@ -17,6 +17,7 @@ import {
   runningNetworks,
   _resetIndexerLoops,
 } from "../indexer";
+import { Asset, Networks } from "@stellar/stellar-sdk";
 import { getRpc, validateNetworkConfig, _resetRpcClients } from "../rpc";
 import { currentNetwork, enabledNetworks, parseNetwork } from "../network";
 
@@ -82,6 +83,11 @@ describe("enabledNetworks", () => {
 });
 
 describe("per-network watch lists", () => {
+  it("matches the Stellar SDK's native SAC derivation", () => {
+    expect(DEFAULT_XLM_SAC_MAINNET).toBe(Asset.native().contractId(Networks.PUBLIC));
+    expect(DEFAULT_XLM_SAC_TESTNET).toBe(Asset.native().contractId(Networks.TESTNET));
+  });
+
   it("defaults each network to its own native XLM SAC", () => {
     // The bug this prevents: reading STELLAR_NETWORK inside the resolver, so
     // both loops watch the same chain's SAC and one indexes nothing.

src/__tests__/sacDetect.test.ts

@@ -7,6 +7,7 @@
  */
 
 import { xdr } from "@stellar/stellar-sdk";
+import { DEFAULT_XLM_SAC_MAINNET, DEFAULT_XLM_SAC_TESTNET } from "../indexer";
 import {
   executableIsSac,
   instanceValIsSac,
@@ -17,9 +18,6 @@ import {
   type InstanceFetcher,
 } from "../indexer/sac-detect";
 
-// The native XLM SACs are hard-coded as known SACs in the module.
-const TESTNET_XLM_SAC = "CDMLFMKMMD7MWZP3FKUBZPVHTUEDLSX4BYGYKH4GCESXYHS3IHQ4EIG4";
-
 function sacInstanceVal(): xdr.ScVal {
   return xdr.ScVal.scvContractInstance(
     new xdr.ScContractInstance({
@@ -67,9 +65,14 @@ describe("instanceValIsSac", () => {
 });
 
 describe("detectSac", () => {
-  it("returns true for a known native XLM SAC without fetching", async () => {
+  it("returns true for known native XLM SACs without fetching", async () => {
     const fetcher = jest.fn<Promise<xdr.ScVal | null>, [string]>();
-    await expect(detectSac(TESTNET_XLM_SAC, fetcher)).resolves.toBe(true);
+    await expect(
+      Promise.all([
+        detectSac(DEFAULT_XLM_SAC_MAINNET, fetcher),
+        detectSac(DEFAULT_XLM_SAC_TESTNET, fetcher),
+      ]),
+    ).resolves.toEqual([true, true]);
     expect(fetcher).not.toHaveBeenCalled();
   });
 

src/indexer.ts

@@ -34,9 +34,9 @@ export function resolveNftContractIds(network?: Network): string[] {
 // These are derived from Asset.native().contractId(Networks.PUBLIC / Networks.TESTNET)
 // and serve as the backwards-compatible default when SAC_CONTRACT_IDS is unset.
 export const DEFAULT_XLM_SAC_MAINNET =
-  "CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC";
+  "CAS3J7GYLGXMF6TDJBBYYSE3HQ6BBSMLNUQ34T6TZMYMW2EVH34XOWMA";
 export const DEFAULT_XLM_SAC_TESTNET =
-  "CDMLFMKMMD7MWZP3FKUBZPVHTUEDLSX4BYGYKH4GCESXYHS3IHQ4EIG4";
+  "CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC";
 
 /**
  * Resolve the list of SAC contract IDs to watch.

src/indexer/sac-detect.ts

@@ -26,8 +26,8 @@ import { resolveNetwork, type Network } from "../network";
 // The native XLM SAC on mainnet and testnet. These are fixed by the network and
 // never change, so we short-circuit detection (and any RPC call) for them.
 const KNOWN_SAC_IDS = new Set<string>([
-  "CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC", // mainnet native XLM
-  "CDMLFMKMMD7MWZP3FKUBZPVHTUEDLSX4BYGYKH4GCESXYHS3IHQ4EIG4", // testnet native XLM
+  "CAS3J7GYLGXMF6TDJBBYYSE3HQ6BBSMLNUQ34T6TZMYMW2EVH34XOWMA", // mainnet native XLM
+  "CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC", // testnet native XLM
 ]);
 
 // ─── Pure helpers ─────────────────────────────────────────────────────────────